Microlattice structures, such as those disclosed in the '989 patent, have numerous applications, for many of which a structure of a certain minimum size is needed. The fabrication method disclosed in the '989 patent involves forming microlattice structures by exposing a suitable liquid photomonomer to collimated light through one or more photomasks. Such a liquid photomonomer may undergo a refractive index change during a photo-polymerization process, which may lead to a formation of polymer optical waveguides. If a monomer that is photo-sensitive is exposed to light (typically UV) under the right conditions, the initial area of polymerization, such as a small circular area, will “trap” the light and guide it to the tip of the polymerized region, further advancing that polymerized region. This process will continue, leading to the formation of a waveguide structure with approximately, or about, the same cross-sectional dimensions along its entire length. A photomask with a two-dimensional pattern of apertures may be used (or utilized) to create a three-dimensional polymer microstructure, when a tray of photomonomer is illuminated from above, through the photomask, by collimated light from several different directions.
The thickness of the microlattice formed using (or utilizing) this fabrication approach is limited by the extent to which the collimated light is able to propagate through the waveguide with sufficiently little attenuation to continue polymerizing the monomer at the end of the waveguide. Thus, there is a need for a system and method of fabricating a microlattice structure not limited in thickness by the extent to which the collimated light is able to propagate through the waveguide.